1. Technical Field
The present invention relates to a yellow ink composition used in ink jet recording methods; an ink set comprising the yellow ink composition, a cyan ink composition, and a magenta ink composition; an ink jet recording method used to make a print by applying a reaction solution and an ink composition to a recording medium; and a record made by the ink jet recording method.
2. Related Art
Ink jet recording methods are printing methods used to make prints by applying fine droplets of ink compositions to recording media such as paper sheets. The ink jet recording methods are characterized in that high-resolution, high-quality images can be quickly printed with relatively inexpensive devices.
An ink composition used for ink jet recording usually comprises water, which is a principal component; a coloring component; and a humectant, such as glycerin, for preventing clogging. Examples of the coloring component include various types of water-soluble dyes, which are widely used because colorants available for the water-soluble dyes are high in chroma, rich in type, and water-soluble.
However, some of dyes have undesirable properties, for example, low light resistance and water resistance; hence, prints made using ink compositions comprising such dyes have low light resistance and water resistance. Although ink jet paper sheets including ink-absorbing layers are improved in water resistance, plain paper sheets are insufficient in water resistance.
Pigments are superior in light resistance and water resistance to the dyes. In recent years, it has been studied that the pigments are used as coloring agents for ink compositions for ink jet recording for the purpose of improvement in light resistance and water resistance. The pigments are usually insoluble in water. Therefore, in the case where the pigments are used for aqueous ink compositions, stable aqueous dispersions prepared by dispersing the pigments in water need to be used to prepare the aqueous ink compositions. For example, the following inks have been proposed: an aqueous pigment ink prepared by dispersing a pigment in water with a surfactant or a polymeric dispersant, an aqueous pigment ink comprising a self-dispersing pigment having a water-soluble functional group, and an aqueous pigment ink comprising fine colored particles comprising a pigment coated with a water-soluble resin.
In view of the use of the pigments as coloring agents for ink jet recording inks, the pigments are superior in light resistance and water resistance to the dyes; however, the number of types of colorants available for the pigments is less than the number of types of colorants available for the dyes. Before a pigment is actually used to prepare an ink jet recording ink, the pigment needs to be evaluated for hue in addition to light resistance and water resistance. For example, JP-A-2000-345080 discloses a yellow ink composition comprising a specific pigment having high light resistance and two specific pigments having excellent color developability. Furthermore, JP-A-10-120956 discloses that the use of an ink set comprising a cyan ink composition, a magenta ink composition, and a yellow ink composition is effective in printing an image having a good hue, high light resistance, and high water resistance.
The inventors have found that an ink set comprising a yellow ink composition, magenta ink composition, and cyan ink composition each comprising a specific pigment is useful in printing an image having a good hue and high light resistance by a color ink jet recording method and is effective in obtaining a record having a good balance between sharpness and thickness by one-path quick printing. The present invention is based on this finding.